Concentration of solution in cross-flow rotating packed bed contactor

• Concentration of liquid by evaporation of volatile species into unsaturated gas.
• Experiments carried out in cross-flow rotating packed bed.
• Smaller equipment volume required compared to thin film evaporator.

Thin film evaporators are traditionally used to concentrate heat sensitive liquid foods wherein thermal energy is supplied to evaporate the volatile component in the solution generally maintained at its boiling point by application of vacuum. In this study, a sub-cooled solution was contacted with an unsaturated gaseous stream in cross-flow rotating packed bed (RPB) to evaporate the volatile component. The performance of the equipment was studied for concentration of aqueous potassium chloride solution. The maximum evaporation rate achieved at an optimum air flow rate, liquid flow rate and rotor speed determined using response surface methodology was 2.4 kg/h. Comparison of water evaporation rate with vertical thin film evaporators suggested the feasibility of achieving higher evaporation rate per unit contactor volume by carrying out the process in RPB.